region splits from the main national output. In the United Kingdom, BBC One Scotland, BBC One Northern Ireland and BBC One Wales often opt out of the main BBC One schedule in favour of regionally relevant programming. In a similar manner, local television newsrooms present regional news following national news bulletins—the practice having been popularised by current affairs programmes Nationwide and Sixty Minutes—after which they would opt into the national programme again. Opting out was also common throughout telethons, such as Children in Need, where regions separate to transmit local coverage. Technical description An opt-out is the process of a regional entity inserting its output into a tributary of an otherwise complete national broadcast distribution feed, creating a local variation in output. Being a non-commercial broadcaster, the BBC has no need to play out local commercial spots, thus a regional node will typically only output programme material during the local news. Rather than each region having to control or monitor output that is being relayed from a central source, the region will step back from the network, allowing the central source to directly feed its transmitters. The central source is a national feed, which is complete in itself including all continuity, timing, announcement and programme elements. The region interposes to broadcast its element locally, in place of a programme in the national feed, by bringing itself into the network (cold-opt) in preparation for the start of the regional element (warm-opt). Within BBC English Regions, the opt-out usually takes place within equipment located within the region's own central technical area. This is not always the case though; for instance the output from BBC Hull, which feeds the Belmont transmitter, is actually switched at BBC Leeds, and the Channel Islands opt-out occurs at Plymouth on the UK mainland, although the programme content comes from both Plymouth and Jersey. Considerable variation can exist between the signal paths for digital (DTT and DSat) and analogue transmissions, leading to great complexity in the opt-out logic. Commercial broadcasters such as ITV, Channel 4 (with S4C) and Channel 5 distribute their programmes to regions complete with local advertising and regional programme variations. Regional programmes, although they may be produced in a particular region, are sent to a centralised play-out facility as contributions for insertion into the regional broadcast feed. BBC programmes in Scotland, Wales and Northern Ireland are broadcast from their own play-out facilities in Glasgow, Cardiff